The purpose of the invention is to develop desirable magnetic recording properties in plated thin-film magnetic recording media. The principal properties which can be controlled by this new process are media noise, which can be significantly reduced from the level obtained by prior art methods, and coercive force, which can be controlled over a wide range.
The growth mode of thin films deposited by plating or other methods can be controlled by characteristics of the surface upon which they are deposited. In the prior-art plating processes no special effort is made to manipulate the surface upon which the magnetic layer is deposited, other than to assure its cleanliness. Using the previous processes, adequate properties are sometimes obtained, but the product is not easily made to be consistent over time, nor have the sources of the inconsistencies been determined. The prior processes also yield inadequate control over coercive force, and media noise is not as low as desired. In the prior plating practice of U.S. Pat. No. 4,581,109, a nominally clean surface of electroplated Ni-P is used as the underlayer upon which a Co-Ni-P magnetic layer is electroplated. The electroplated Ni-P layer is deposited on a polished electroless Ni-P layer.